Sampling methods for estimating change in forest resources

Scott, Charles

Changes in forest resources have been estimated in a variety of ways. This paper focuses on extensive forest surveys rather than on sentinel-site investigations. The sampling design and plot design used are key to precise estimates of change. Alternative sampling designs include temporary surveys, Continuous Forest Inventory, and Sampling with Partial Replacement. Each can be used in conjunction with stratified sampling or double sampling for stratification. Plot designs can involve variable-radius or Bitterlich sampling for trees, and fixed-area plots for most attributes. In extensive surveys, it is efficient to group plots into clusters. Plots must be sampled at a frequency that is commensurate with the rate of change, degree of interest, and funding available. Often, plots are less than a hectare in size and spaced widely across the population. Continuous Forest Inventory, with or without stratification, is efficient for estimating current values, net change, and components of change. Much work remains in scaling to understand landscape-level interactions and to identify stressors and indicators of forest health and sustainability.

Sampling methods for estimating change in forest resources

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